Electric discharge device with auxiliary electrode



May 23, 1950 A. LATOUR ETI'AL v ELECTRIC DISCHARGE DEVICE WITH AUXILIARYELECTRODE Filed Oct. 10, 1947 4 Sheets-Sheet l May 23, 1950 LATQUR ETAL2,508,954

ELECTRIC DISCHARGE DEVICE WITH AUXILIARY ELECTRODE Filed Oct. 10, 1947 4Sheets-Sheet 2 May 23, 1950 LATOUR r 2,508,954

ELECTRIC DISCHARGE DEVICE WITH AUXILIARY ELECTRODE 4 Sheets-Sheet 3Filed Oct. 10, 1947 May 23, 1950 LATQUR ETAL 2,508,954

ELECTRIC DISCHARGE DEVICE WITH AUXILIARY ELECTRODE Filed Oct. 10, 1947 4Sheets-Sheet 4 Ill/11111101 Miami}. M

of the electrode l.

gaps, one of the electrodes being shown in a cross-section passingthrough the axis.

Figs. 1 to 8 represent different forms of construction of spark gapsaccording to the invention, one of the electrodes being shown in across-section in a plane through its axis.

Figs. 9 to 15 represent various applications of the spark gapshereabove.

Fig. 1 shows a design of a spark gap according to the present inventionin which the conducting path formed by the ionized gases is blown off bya blast of compressed isolating gas, f. i. compressed air.

In this Figure 1, I is the main spark gap and 2 the auxiliary electrode.I and l have a respectively toric form or a form approaching the toricform and the form of a top. The are kindling electrode 2 is located inthe interior of a blast pipe of insulating material, to which compressedair is supplied by the pipe II. The device works as follows:

The distance between the electrodes 1 and l is so calculated that inabsence of any ionising effect, no possibility for a fiashover is given.But as soon as a sufiicient potential difierence arises between i and 2an arc strikes between these two electrodes on the path marked by adotted line. The hot. gases, however, produced by the action of thecompressed air on the arc, form a straightlined jet of strongly ionisedgases, which attain almost instantaneously the extreme point Aconducting path is thus established between the electrodes l and lgiving rise to an are between these electrodes. If this arc is to beallowed to subsist during a notable time without deteriorating thesurface of the electrodes 1 and I, it must be obliged to move rapidly,which is easily obtained, f. i. by a ma -.netic field with radialfieldlines created by two opposite coils M and M preferably located atthe interior of said electrodes.

. Instead of using compressed air, use may be made for the blast of theelectrode 2 of the property presented by numerous chemical materials toproduce under the influence of the arc various gaseous emanations. Undersuch conditions, the

. auxiliary electrode 2 is simply located at the interior of a tube 6made of convenient gas-producing material, as shown in Fig. 2.

Fig. 3 shows a variation of design in which the auxiliary electrode islocated at the interior of the main electrode l: for this purpose theelectrode l 'is provided with an internal chamber 3 opening through theorifice 4. The auxiliary electrode 2 is so located in this chamber thatits extremity lays near the orifice 4. The auxiliary electrode isisolated from the main electrode l by a sleeve U 5. Compressed gas maybe introduced into the cavity 3 by a duct ll. The flow of this gasthrough the orifice 4 does not cause an are be- 'tween the mainelectrodes, but as soon as an arc strikes between 2 and 4 the compressedgas is ionized, a conductive path is created and the are strikes betweenthe main electrodes. Although in the present case the walls of thecavity 3 are metallic, there is no obstacle to combine this device withthat in Fig. 2, in which the walls are of a gas-producing material.

Fig. 4 is an example of an embodiment of the invention as it has beendescribed hereabove.

In this figure, the main electrodes I and l' have a hemispheric form andare so opposite to each other, that their surface is symmetric withrespect to the axis X--X1. According to the invention the main electrodeI is provided with an chamber are formed by the tube 5, which in thesame time serves as support and as insulator for the auxiliaryelectrode. Eventually the tube 5 may contain a sleeve 5 of a materialother than the material the tube 5 is made of. It may be advantageous tochoose as material for the sleeve 5 one which produces gases under theaction of the spark or the electric arc. This material may eventually bemodified in order to have it produce more or less conductive gases, byincorporation of suitable metallic oxides.

In order to secure a better understanding of how the device functionsaccording to the invention, Fig. 4 shows a particular application inwhich the spark gap is supposed to act as closing relay. In this diagrami, is a source of direct or alternating current, 8 is any kind ofreceiver, which is intended to be switched at a given moment into thecircuit of the source by intermediary of the spark gap 1 and I. 9 is anauxiliary source of convenient tension. Form of and distance between theelectrodes is so chosen that, in absence of any notable ionisationagent, the tension applied to the electrodes is insulicient as to causea discharge. If, at a given moment the main circuit l'--8llis to beclosed, it sufises to close by the switch ID the auxiliary 49lil2-wherein, in fact the extremity of the auxiliary electrode 2 and theWalls of the orifice 4 form the poles of an auxiliary gap. When theswitch H] is closed, a flashover occurs between 4 and 2 whereby thetemperature of the gases in the chamber 3 is considerably raised causingthe expansion of the gases which flow in form of an ionised andconductive jet through the orifice 4 and give rapidly rise to adischarge between the electrodes I and i. This effect may still beincreased by making the walls of the chamber 3 of a material, whichunder the action of the auxiliary arc produces gases, or by making theelectrode 2 or the orifice 4 of a relatively volatile metal. ,Asmentioned above the conductivity of the gases streaming out through theorifice, 4 may be increased at will by adding to the materials, theelectrode 2, the walls of the orifice t or of the chamber 3 are made ofconvenient metallic salts or metallic oxides (alkaline, earthy alkalineor radio active metals).

As the speed of the conductive gases spirting from the orifice 4. isfinite a certain time lag exists between the discharge of the auxiliaryspark gap 2-4 and the discharge of the main spark gap ll. It may be incertain cases advantageous, in order to reduce this time lag, to providethe electrode I' too, with an auxiliary gap, so that the whole set issymmetrical to the axis XX1. In this case, the two jets of kindlinggases meet halfway whereby the time lag for the main discharge isconsiderably reduced. It is understood that this form of realisation isapplicable to all examples given hereafter:

The switch It] is by no means indispensable. In fact, the source 9 maybe provided such as to produce one or more tension impulses producingthe auxiliary discharge between 2 and 4. In a general way, the sourcemay be constituted by any known source producing a tension (battery,accumulator, dynamo, rectifier, alternator, transformer, condenser,resistance or impedance through which passes a current and so on).

The regulation of the flash over tension ofthe amazon -aiuxiliarysparkgap Q I may-be obtained by dis placing the kindling-electrode 2' withrespectto the'g orifice 4. Or, by inserting into the auxiliary circuit aregulator gap, eventually provide'd -with a-lolow out device. If thepotential of the electrodes-is to be fixed with respect to each other,they may be connected by a convenient resistance, inductance orimpedance.

When the discharge between 2 and 4 has begun and has' served itspurpose, it is desirable to extin'guish it as quickly as possible. Ifthe tension providedby the source Sis an alternating-one, theextinguishing effect of the gases leaving-the chamber 3 is generallysufiicient, this effect-may be, moreover, increased by inserting intothe auxiliary circuit a resistance; the ohmic value of which decreasesrapidly with the applied tension ora spark gap withblow out many otherinterrupting device, eventually in combinationwith the switch l0.

Allpreceding considerations are valid forthe example followinghereafter, which are given merely-for a better understanding of thespirit of the invention and which by no means @are limitative.

Ifthe 'main discharge assumes the form of an arc of high power andnotable duration; it may become useful to displace rapidly the root ofthe arconthe surf-ace of the main electrode by means of a convenientblow out, f. i. a magnetic blow-out.

It is advantageous togive the main electrode the form of an appropriaterevolution body, f.i. the form of a torus.

Fig.= 5 shows a device of that kind. i i represents the main electrodesupposed-to cooperate-with a similar electrode symmetrically placed with--respect to the axis X--X1. Using-the same references as before Zis theauxiliary kindlingelectrode, 3 -the compression chamber,litheorificeelectrode, 5 the insulating tube etc. Thecircular'di'splacement of the main arc, spirting on the partofthesurface 12 which is nearest to the symmetrical main electrode, issecured by a magnetic field with the lines of force of which are asmuchas possible perpendicular to the axisof'th'e arc.

This field may be created by means of a winding-I3 coaxially placed onthe rear face of the electrode l. A single main electrode may beprovided with'such a winding, however, each electrod may have its ownwinding, but-inthis case the-extremitiesof the windings which areopposite each other must have I the same magnetic polarity. Thesewindings may be excited by an independent source of supply, or may beconnected only-in 'seriesw-ith the main electrodes and this way eX citedby the current which flows in the main arc. A strengthening anda betterdistribution of the magnetic field is obtained by providi'ng a magneticcore with a more orless extending extremity If the utilised magneticfield 'is' alternating, it is advantageous to split radially the main:electrode provided with a winding. It is not essential to place-theauxiliary gap 2-4 at the plac'e indicated in Fig;- 5, it may be placedoutside thepath of the main arc f. i. in the core l'4-along the axis ofthe main electrodes. The increase in ignition lag resulting 'byso' doingneed not-be an inconvenience.

In certain applications, it is necessary to reestabli'sh very rapidly,after extinction of the main arc, the dielectricstrength of the gapseparating the main electrodes. This may advantageously be ach'ievedby'a current of compressed 'airen"- Veloping, completely or partially,the active sur- I metrically arranged '-with respect -'to the-axis: l6and [9 are the terminals off the- X'X1. auxiliary spark gap;whiletheftermi-riail 19 is. equally the terminal- 0f the main electrodeI The air blast gushingthrougho'ut the tip i'flof the: nozzle does notdisturHthe kind-lingof the -main are by the conductive gas jet spiiting'fro the orifice '4. But this'air blast" prevents;-asesoon"- a s themainarc has been extinguished any restrik ing of the arc, which-might occurby exterior-in fluences; and without intervention of-the auxil iary'spark gap, which, 'of-course, is supposedto blow out as soon as itsfunction as igniter 'has been accom'plishedl r Fig. 7 shows anotherembodiment of the "in"- vention, comprising means for I dielectric regeneration "of the gap "between the 'mainelectrodes, which-in thepresent case-are tubes with a-toricshape or their "extremities i and IThey are located iiithe interior of an enclosure, in which,- bymeans-notshownj -a-pressure of 00mpressed gas or air is maintained. Theinterior of the tubes *l'|'* communicates 'with theatmosphere; thissecures-a gaseous fiow inthe direc-- tion indicated by the arrows thanksto-which the gaseous mediumsituated between the electrodes l--lisconstantly-and rapid1y renewe'd-.- As' in the previous example, themain electrode l provided with an auxiliary kindling "electrode 2 withits compression chamber 3 and its'orifice electrode 4. Theinsulating-'tube-imayeventually be sheathed by a'metallic tube '22,destined to protect the tube '5 against the action of the hotgasescirculatingat the interior 'of the-main electrode The mainelectrode 1 maybe provided too, with -an'-auxi1iary kindlin electrode 2preferably placed' opposite the auxiliary electrode -2 and coaxiallywithit;

In a device accordingto Fig'fi 7, the conductive gases streaming outthrough the orifice ll might be disturbed in theirki'n'dling function bythe deviation imposed upon them "by thegaseous blast provided-for thedielectric regeneration of the gap' |--I. This "inconvenience ma ybe'over come by prOvidingtheorifice-l such as tohave an inclined axiswith respect to-"the'-ax-is of the electrode; This-inclination cancels,partially; or totally, the effect of the deviation'impose'd on theconductive -jet by 'thegas blast mnemonductive'jets now follow aj-path'shown in dotted lines in Figf8and meet'easily According to theinvention-all 5 spark-gaps may be provided, ifnecessary, withaconvenientcooling, f; i. a'Watercirculationyapplied as well to the mainelectrodesas tothe auxiliary kindling electrodes in order to secure anoperation of long durationi The following figure show various examples-6f application of --spa'rk-g'aps -herebefore-described;

"For convenience of-= drawingg they are rein-ethat each applicationnecessitates the most appropriate type of the spark gap in order toattain the desired result, so that a careful choice has to be made amongthe type described hereabove.

Fig. 9 shows a spark gap l-l' according to the invention used as closingswitch and playing the part of a synchronised relay, capable to closethe circuit at a predetermined point of the curve of the alternatingtension furnished by the generator 23 supposed to supply some kind ofreceiver 24. In order to attain this object, the kindling electrode of lis connected f. i. to the secondary winding of a transformer, thetension of which may be at will dephased by some angle with respect tothe tension of the generator 23 by anappropriated means, i. i. aninduction regulator 21. In order to close the main circuit 23, l|'24 ata given pre-fixed point of the curve of the electro-motive tension ofthe generator, it suffises to regulate previously the inductionregulator and then to close the switch 28. Supposing that the crestvalue of the secondary voltage of the transformer 25 is barely higherthan the flash-over voltage of the auxiliary sparkgap 2-4, it will berealised that the are on the auxiliary spark-gap will occur at the firstinstant following the closure of 26, in which the secondary tension of25 passes through its maximum. In order to prevent the surge, caused bythe closing of 26, to flash-over prematurely the spark-gap 2-4 theprimary winding 25 of the transformer is shunted by a non-inductiveresistance 26. The intensity of the kindling discharge may be regulatedby any suitable impedance 29 inserted into the circuit.

It will be realized that the duration of the auxiliary arc, produced bythe crest value of the tension, should normally not be longer than aquarter of a cycle, the gases streaming through the orifice 4 having toensureits extinction or rather to prevent its restriking and itsdegeneration into a permanent arc. If however this action isinsufficient, an appropriate device may be inserted into the circuit, aexplained heretofore (a blow out spark gap, resistance with aresistivity varying according to the tension, automaticcircuit-breaker). In order to increase the precision of the kindling, itis advantageous to use a tension curve as pointed as possible anddiffering from the normal sinusoidal curve. Such a curve may be obtainedby any of the numerous and well known means, particularly by aresistance connected in series with a transformer or an-inductance withsaturated magnetic core. If the main arc burning between the electrodesll' is to last a notable time and with a high energy it is advantageous,in order to prevent an exaggerated wear of the electrodes, to use somedevice, ensuring the displacement of the roots of the arc at theirsurface. Such a device is shown f. i. (in Fi 3).

The spark gap l! may be also short-circuited by a switch 30 which closesimmediately after the flash-over of the spark-gap. This closure may becommanded f. i. automatically.

A result similar to that obtained by the diagram shown in Fig. 9 may beobtained as shown in Figure 10, by an alternator, the armature of whichfeeds the primary of the transformer 25. If the generator 23 is a rotarymachine, the alternator 3| may be mechanically coupled to it. If,however, the generator has a static character (f. i. the secondary of astatic transformer), the

coupling of the alternator may be realised electrically by a synchronousmotor. In both cases,

the regulation of the de-phasing of both voltages is achieved bymechanical angular shifting of the stationary part of the transformer.The kindling of the main arc is achieved in the same manner as describedfor Fig. '7, by closing the switch 26. It may however be also obtainedby closing the switch 34 which controls the excitation circuit of thealternator 3|.

Finally, as shown in Fig. 11, the alternator 3| may be replaced by arotary spark-gap 36 transmitting at the right moment to the kindlingspark gap 24 the energy previously stored up in a condenser 37, chargedby a convenient source 40 through the resistance 38 and controlled by aswitch 39. The closure of the switch determinates with a time lagcorresponding to the suificient charging of the condenser, the closingof the main circuit by flash-over of the spark-gap ll The examples shownin Figs. 9 10 and 11 have considered hitherto only the case of adefinitive and permanent flash-over of the main spark-gap |-I. If thisspark gap is however provided with a device, securing the dielectricregeneration of the gap between the electrodes, as it is the case withthe device shown in Figs. 6 and 7, then arises the possibility ofperiodical extinction and restriking of the are, a possibility liable toindustrial applications as f. i. of current rectification.

The arrangement in Fig. 11, f. i. is very Well suitable to work as a onephase rectifier, as the kindling electrode can only operate one time percycle, a rectification is only possible by polarising the auxiliarycircuit either by inserting a continuous electro-motive force, either byeliminating one of the alternations by a rectifier. A polyphas-erectification is obtained in the usual way by using as many sprak-gapsas there are phases to be rectified and it is understood that alldevices and connecting methods used with thermo-ionic rectifiers, areapplicable, here too, particularly the multiple balance inductances andneutral points.

The spark-gaps according to the invention are equally suitable to beused for the realisation of schemes for indirect tests ofcircuit-breakers as shown in Figs. 121314- and 15.

In Fig. 12, 4| is the circuit-breaker to be tested, 42 a generator witha comparatively low tension, and high current intensity (alternator ortransformer secondary) the output of which may be adjusted by means ofan inductance or impedance 43. The spark gap l-l' is connected in serieswith the circuit-breaker 4|, the pole of which nonconnected to thespark-gap may eventually be grounded. The generator 42 feeds on theother hand, the primary 45 of a step-up transformer, the secondary 45 ofwhich is connected through a resistance 47 to the connection between thecircuit-breaker and the spark-gap. The gap between the electrodes i-l'is established so that when the auxiliary gap is out of action, theflash-over voltage is superior to the tension of the secondary 46.Supposing that a closing test has to be made, the arrangement works asfollows:

The circuit-breaker is open and subject to the sum of the tensions ofthe generator 42 and of the winding 46, said sum of voltages beingprecisely the test voltage. On the other hand the tension between theelectrodes is zero because no current flows yet in the resistance 41. Nodischarge can occur therefore between the electrodes I and I. Y

.Itham-"the icircuitebreaker'is closed an; arc will; strike; between;its: contacts as-soon as the latter are separated by a distance.corresponding toi thez flash, over distance of the. test voltage. Thecurrent flowing in-this. arc fiowsalso through the resistance '41 and.creates. at its terminals a- --difference" of: potential which appearsin the same-time between the electrodes 2 and. and strikes-an areontheelectrode 2. The compressed air-bla-st passingthrough-the blastnozzle 3;blows'the arc-between 2 and lwin such'a directionethat ithelatter-starts the: discharge of the mainsspark=gap From this momentronthe generator feeds directly the circuit breaker 4|, and if the. timelag: between theinitial discharge and the arc of the main spark -gap-.is negligible; it-may be saidthat things have-"occurred :.-asif thecircuit-breaker had been subjected to" the action of asourcesupplying'the samecurrent as the generator 42 under a tension" equal -tothe-sumof tensions of'thegenerator 42 and' ofithe step-up winding 46.

"To the test-circuit described hereahove may be added recording deviceslike a tension divider 49-" andthe shunt 48.- An oscillograph' O1 isthen connected to the shunt 48 and another osc'illograph, f. i. acathodic oscillograph, Oz to -the tension divider 49;

Itwill be realised that at the instant when th'emain dischargeoccurs-in'thespark-gap the tension at the terminals of the primary 45drops considerably, due to the fact of the increase of current in thegenerator 42 and in the inductance 43. It is the same for the secondary46i This drop-of tension creates favorable conditions permitting; to thedevices provided for the extinction 'of' the auxiliary are between 2 andI to operate with full efiiciency. Should, however, thisdevice notbesufiicient, then the acceleration of the extinction of the auxiliary arcmay generation of gas; similar to the spark-gap shown in 'Figs. 2 and i.'It is understood'that in applications. described hereabove' or.hereafter, either the. :c-neor the other form spark-gap withcontrolledkindling of the arc may be used, according to the individual.case, without departing from thegeneral spirit of the present invention.

The sparkeg-a'p: as ishown. above suits perfectly forjclosure testsz. Ifthe spark-gap is to be used for opening tests, it becomes necessary toprovide the spark-gapWI-Af Witha device securing a rapid dielectricregeneration of its gap. For this purpose devices; as'describ'ed by theFigs. 6 to 8, may advantageously be used! The whole =arrangement'worksthen: as" follows:

Thewcircuit-breaker 4| .at..the beginning. is. closed,'.consequently acurrent ,flows, as soon as the-.switch'44'is closed; 'throughtheresistance 41,. producing a' discharge. in ,thespark gap...Whereuponijthe generation supplies its fullecurrrentto.the-circuitbreaker- 4|. .As long-asthe latter remains closed'or aslong as its contactsree main too near to each other, to permit thebreaker to attain a sufficient breaking capacity, the main are betweenrestrikes after each extinction in spite of the device for dielectricregeneration.

5 atits terminal the difference of potential which causes.- theelectrode 2 to kindle the arc every timethattherecovery tensionreappears at-the terminals of thebreaker 4|. If. at a given momentthe.dielectric strengthbetween the contacts of thebreaker 4| has becomesufiiciently strong, as to stand the recovery tension whereby it .is

taken. as granted-that .all. measures havebeen.

taken bydesign to secure thatthe mainelectrodesof the spark-gapwillstand this tension too,.no. current flows. through the resistance 41-,the difference-of.- potentialbetween the ,electrodes-2-4-lis zero; andthe main spark gap l-l" cannot flash-over. The circuit-breaker 4| willthushave'interrupted-the.full current supplied-by thegenerator 42 undera tension which accordingtotherratio ofthestep-up transformer 45, .46:mightbe severaltimes higher than the own-tenesion of the generator 42.

If the isolating switch is to be closed, an appreciable time before thecircuit-breaker. 4| rlS able tooperate a break, it might beuselessoreven harmful to have the -main are burning.

during this time between the electrodes This inconvenience may be"avoided'by making: I theelectrodes movable with respect to each.

other and by maintainingthem in contact as long as the. circuit-breakeris not able to operate-a: break. Such an arrangement may be'realised inan advantageous manner by mounting one of. 5, the two electrodes or bothintegral with apiston, which is pushed bya spring in a direc-- tion suchthat the two electrodes are maintainedpressed together, when nosufficient pressure exists within the casing by which they aresurrounded. As soon as the de-ionising agent==is blown into the casingthe electrodes part,.and are automatically set in correct positionthuspermitting the-spark gap to recover very rapidly its normalproperties.

Another solution isto-leave the electrodessof "the spark gapstationaryand to connect: in parallel with the spark gap a circuit breakerv ofsuitable. breaking'capacity which is opened:

only. at theinstant when the circuit-breaker 4|] is able to operate."mount the transformer 45, 46 according to the Fig. 13.

calls'however, for. the same tension at the terminals oi thecircuit-breaker 4-! as previous, for. a. higher .ratio of the step-uptransformer andzis therefore .fromgthispoint of view less advan-'tageous than the arrangement shown in Fig. 13.-

.In certain cases, f. i. when the tension is -.so

high thatan. important gap betweenthe electrodes becomes necessary andthe time lagforthe kindling. of the main arc is to be re-- 65:? duced,there is advantage to use two kindling.

auxiliary-electrodes-l -and Z as shown in Fig. 15. In. this case, it is.not indispensable that theelectrodes 2 -.and 2 kindle simultaneously,owing to -.the.-fact that they are. subject tosame ten--70'vsionscproducedby resistances of equal. value 41 amt-.415. Inthecontrary-these resistances-=may haveydifierent values ande41' f. i;-have alrigh ohmic value. The kindling of the auxiliary spark gap 2-4then will be a result of the in- 75 crease of the auxiliary currentproduced by the It is not indispensable to Another way to connect thetransformer to'the circuit is shown in 'Fig. 14, and consists inconnecting the'common point ofthe: primary and secondary windingstothegrounded -section of the main circuit. This arrangement initial kindlingof the spark gap 2- 4'. Each kindling electrode may have in its owncircuit, as explained above, its own regulating elements, such asresistances 48-48, impedances, spark gaps with or without blow 'out,supplementary alternating supply sources ensuring a correct kindling andextinction of the auxiliary arc.

Finally, whatever the considered application might be, in the case ofvery high tensions, according to the invention, several spark gaps maybe connected in series, whereby the usual measures are to be taken toensure a uniform repartition of the tension on the spark gaps. This maybe achieved by connecting each spark-gap to a portion of the winding ofthe step-up transformer or by shunting each spark gap by an ohmicinductive or capacitive impedance of suitable value. p

The invention must not be arbitrarily limited to the few examples ofembodiments described hereabove. The invention covers all possiblemodifications of design according to the application.

What we claim is:

1. In an arrangement for indirectly testing circuit breakers or thelike, in combination the device to be tested, means connected to saiddevice for supplying electric power at relatively high voltage,constituting the high voltage circuit, means connected to said devicefor supplying electric power at relatively high current, constitutingthe high current circuit, a discharge gap in said high current circuit,an impedance in said high voltage circuit, and an auxiliary dischargegap controlled by the voltage drop across said impedance and mounted inrelationship with said first mentioned discharge gap promoting bybreaking down the ionization of said first mentioned discharge gap.

2. In an arrangement for indirectly testing circuit breakers or thelike, in combination the device to be tested, means connected to saiddevice for supplying electric power at relatively high voltage,constituting the high voltage circuit, means connected to said devicefor supplying electric power at relatively high current, constitutingthe high current circuit, a discharge gap on said high current circuit,an impedance on said high voltage circuit, an auxiliary discharge gapmounted in parallel to said impedance and in spatial relations with saidfirst mentioned discharge gap the spatial relation of said dischargegaps being designed for said first mentioned discharge gap being ionizedby the ionized gases issuing from said auxiliary discharge gap.

3. In an arrangement for indirectly testing circuit breakers or thelike, in combination the device to be tested, means connected to saiddevice for supplying electric power at relatively high voltage,constituting the high voltage circuit, means connected to said devicefor supplying electric power at relatively high current, constitutingthe high current circuit, a discharge gap on said high current circuit,an impedance on said high voltage circuit, an auxiliary discharge gapmounted in parallel to said impedance and in spatial relations with saidfirst mentioned discharge gap so as to promote said break-down of theauxiliary discharge gap as consequence of the ionization provoked by thebreak-down of said first mentioned discharge gap, the spatial relationof said discharge gaps being designed for said first mentioned dischargegap being ionized by the ionized gases issuing from said auxiliarydischarge gap.

4. In an arrangement for indirectly testing circuit breakers or thelike, in combination the device to be tested, means connected to saiddevice for supplying electric power at relatively high voltage,constituting the high voltage circuit, means connected to said devicefor supplying electric power at relatively high current, constitutingthe high current circuit, a discharge gap on said high current circuit,an impedance on said high voltage circuit, an auxiliary discharge gapmounted in parallel to said impedance and in spatial relations with saidfirst mentioned discharge gap the spatial relations of said dischargegaps being designed for said first mentioned discharge gap being ionizedby the ionization gases of said auxiliary discharge gap, a pressure gassource, and duct means for directing the pressure gas from said sourceto said discharge gap.

5. In an arrangement for indirectly testing circuit breakers or thelike, in combination the device to be tested, means connected to saiddevice for supplying electric power at relatively high voltage,constituting the high voltage circuit, means connected to said devicefor supplying electric power at relatively high current, constitutingthe high current circuit, a discharge gap on said high current circuit,an impedance on said high voltage circuit, an auxiliary discharge gapmounted in parallel to said impedance and in spatial relations withsaidfirst mentioned discharge gap, a pressure gas source, and duct meansI for directing the pressure gas from said source to said dischargegaps, the spatial relation of said discharge gaps being designed for thearc of said first mentioned discharge gap being changed over to saidauxiliary discharge gap in responseto the blast action of the pressuregap.

6. In an arrangement for indirectly testing circuit breakers or thelike, in combination the device to be tested, means connected to saiddevice for supplying electric power at relatively high voltage,constituting the high voltage circuit, means connected to said devicefor supplying electric power at relatively high current, constitutingthe high current circuit, a discharge gap on said high current circuit,in impedance on said high voltage circuit, an auxiliary discharge gapmounted in parallel to said impedance and having an electrode a tube ofgas producing substance having said electrode, the spatial relations ofsaid discharge gaps being designed for the produced gas being directedtowards said first mentioned discharge gap.

ANDRE LATOUR. ROGER CHAMBRILLON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,551,970 Schafer Sept. 1, 19251,739,443 Dunoyer Dec. 10, 1929 1,843,645 Von Issendorfl Feb. 2, 19321,873,963 Jonas Aug. 30, 1932 1,980,459 White Nov. 13, 1934 2,400,457Haine May 14, 1946

